Tiptoeing, creeping and in some cases, galloping along the banks and into wooded areas. But because those aliens are green, they blend in with the native population of trees, shrubs and grasses so the untrained eye often misses them.

A short stroll along Sandy Creek from the firehouse west near Hwy. 96, yielded seven invasive plant species identified in only a few minutes by participants in the Texas Non-Native Invasive Plant Species workshop held at the Jasper Fire Station, Saturday, Jan. 23.

Twenty-nine persons attended the all-day educational seminar led by Mike Murphrey, a Texas Forest Service specialist in both forest pest management and non-native invasive species.

"I have been with the Texas Forest Service for 20 years, ending up in pest management, specifically the pine beetle and the invasive species division. This subject is near and dear to my heart," Murphrey said. "My job is to raise public awareness of the problem and to educate and train citizens to participate in the Invaders of Texas program."

Participants in these programs then become 'Citizen Scientists', able to document non-native invasive species and contribute to the database at texasinvasives.org.

"The Lady Bird Johnson Wildflower Center became concerned a few years ago about invasives displacing native species," Murphrey said. "Invaders of Texas is part of a partnership called the Pulling Together Initiative, a partnership with federal organizations, non-government organizations, the nursery industry, and other stakeholders to address the spread of non-native invasive species in Texas."

Murphrey went on to explain the problem with species that are not native to a particular ecosystem. They can become invasive and choke out other species because they have no natural checks and balances in the new environment. And when that happens, other species suffer. It is a chain reaction.

An introduced species might become invasive if it can out-compete native species for resources such as nutrients, light, physical space, water, and food.

"When native plants are choked out, so are other species such as bugs, worms, animals, and birds," he said. "Invasives are the biggest cause of native extinction."

Although plants may be spread by wind, water and animals, humans contribute their share by unwittingly planting invasives in the landscape or carrying plant material on boats and cars. Over time, these plants invade fields, roadsides, forests, waterways, and wetlands.

For example, those familiar aquatic species that choke lakes and wetland areas here in Southeast Texas are frequently carried from place to place by persons who fail to thoroughly clean boats between putting in at one water source and then another.

Terrestrial plants are commonly spread when people plant them in the landscape and the seeds are spread by birds or other animals.

Some common landscape shrubs, vines, and ground covers that end up in East Texas forests include Nandina (sacred bamboo), Japanese and Chinese privet (ligustrum), non-native wisteria, English Ivy, bigleaf periwinkle, Japanese Honeysuckle, and Japanese Climbing Fern.

A small sample of trees include Chinaberry, Chinese Tallow and Mimosa

Grasses are also on that list and Murphrey found an area of Cogon grass near Spurger that, so far, has defied his attempts to eradicate it.

"I have sprayed it and sprayed it and all I've done is knock it back," he said. "It is not dead, and burning won't help because it loves fire. You can't burn it enough and the pines cannot tolerate that much heat. It spreads by seed and root and everything in that habitat is removed as it spreads. It is costing the State of Alabama millions of dollars to control it."

It is difficult to get an accurate, definitive dollar amount showing the economic impact of non-native species in the United States except that it runs in the billions of dollars. One 2005 estimate is over $138 billion and another reason to be concerned about the spread of noxious plants.

After discussing the problems with invasives, workshop participants took a short walk along a small portion on the south side of Sandy Creek where they quickly found and photographed seven non-natives that are in 'take-over' mode in that area. They also used GPS units to mark the coordinates.

Photographing and mapping these plants is an important part of the Invaders of Texas program. This information is then sent to an on-line database at texasinvasives.org. Since the rate of invasives is increasing and there is a gap in the knowledge about distribution and biology, plus a lack of communication between the state's invasive species stakeholders, this database is important.

"There is not a definitive source of information for Texas," Murphrey said. "There is a gap in our knowledge. We want to define the problem, share information, raise public awareness, and then take action."

That lack of a definitive source of information shows up on the various agencies' lists of destructive species for specific geographic areas. Those lists vary because of underreporting.

Citizen scientists will be able to help fill the gaps on distribution, rate of spread and habitat, therefore contributing valuable information through this state-wide mapping database to those who can do something about it.

In addition, citizen groups like garden clubs, Master Gardener groups and environmental groups are also taking action by hosting outings to eradicate nuisance species in specific habitats where they have permission to do so.

Participants in Saturday's workshop seemed pleased with what they learned.

"It was great and it was what I expected," Joanna McMurry said. "I usually have a hard time staying awake in seminars, but this was so animated that it held my interest."

With its well-used walking trail and central location in downtown Jasper, Sandy Creek Park is an easy place to see the effects of invasive plant species: There are areas where Chinese Tallow Tree is choking out native hardwoods that would ordinarily grow along the steam bank, both species of privet occupy the understory, Johnson grass has usurped native grasses, and Japanese Honeysuckle is smothering everything in its path.

But aliens are also lurking in our own landscapes. That pretty Japanese Climbing Fern so common in local yards is like kudzu, capable of engulfing entire woodlands. Nandina, with its lovely foliage and red berries, can form thick stands in the woods like any bamboo. And those Ligustrums planted as hedges become the nuisance privet that pop up everywhere.

As Mike Murphrey pointed out, not all exotics become invasive; and it does not mean that property owners must stick strictly to native species; however, it is prudent to learn about those that are destructive.